US4392167A - Magnetic head, method of producing the magnetic head - Google Patents

Magnetic head, method of producing the magnetic head Download PDF

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Publication number
US4392167A
US4392167A US06/200,112 US20011280A US4392167A US 4392167 A US4392167 A US 4392167A US 20011280 A US20011280 A US 20011280A US 4392167 A US4392167 A US 4392167A
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United States
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weight
magnetic head
glass
layer
pole pieces
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Expired - Lifetime
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US06/200,112
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Hendrik J. M. Joormann
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US Philips Corp
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US Philips Corp
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Assigned to U.S. PHILIPS CORPORATION, A CORP. OF DE reassignment U.S. PHILIPS CORPORATION, A CORP. OF DE ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: JOORMANN, HENDRIK J. M.
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    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/127—Structure or manufacture of heads, e.g. inductive
    • G11B5/187—Structure or manufacture of the surface of the head in physical contact with, or immediately adjacent to the recording medium; Pole pieces; Gap features
    • G11B5/23—Gap features
    • G11B5/235—Selection of material for gap filler
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/49—Method of mechanical manufacture
    • Y10T29/49002—Electrical device making
    • Y10T29/4902—Electromagnet, transformer or inductor
    • Y10T29/49021—Magnetic recording reproducing transducer [e.g., tape head, core, etc.]
    • Y10T29/49032—Fabricating head structure or component thereof
    • Y10T29/49036—Fabricating head structure or component thereof including measuring or testing
    • Y10T29/49039—Fabricating head structure or component thereof including measuring or testing with dual gap materials
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/49—Method of mechanical manufacture
    • Y10T29/49002—Electrical device making
    • Y10T29/4902—Electromagnet, transformer or inductor
    • Y10T29/49021—Magnetic recording reproducing transducer [e.g., tape head, core, etc.]
    • Y10T29/49032—Fabricating head structure or component thereof
    • Y10T29/49055—Fabricating head structure or component thereof with bond/laminating preformed parts, at least two magnetic
    • Y10T29/49057—Using glass bonding material

Definitions

  • the invention relates to a magnetic head having a core of a magnetizable material which is interrupted by a gap in which at least one layer of a non-magnetizable material has been provided, and to a method of producing a magnetic head, the method comprising the following steps: The formation of a first and a second pole piece of a magnetic material; the machining of a face of each of the pole pieces in such manner as to serve as a gap-defining surface; the provision of at least one layer of a non-magnetizable material on the gap-defining surface of at least one of the two pole pieces; the joining of the gap-defining surfaces of the two pole pieces provided with the said gap layer to secure them together, whereafter a winding is provided around at least one of the pole pieces.
  • Magnetic heads are used to record, reproduce and/or erase magnetic information. They are used in, for example, tape recorders for recording and/or reproducing sound information or picture information.
  • United Kingdom Patent Specification No. 1,317,634 discloses such a magnetic head and a method of producing same.
  • the layer of non-magnetizable material consists of a glass having a softening point of 450°-650° C., for example a glass containing 60% by weight of PbO, 16% by weight of SiO 2 , 14% by weight of B 2 O 3 and 10% by weight of ZnO.
  • the glass may be provided by means of sputtering.
  • a second layer consisting of a non-magnetisable material, metal oxide, metal boride, metal nitride, silicon oxide or a ferrite which is non-magnetizable at ambient temperature, may be provided between the layer of non-magnetizable material and the core of magnetisable material.
  • the glass used in the known magnetic head has the disadvantage that the composition of the glass is not constant, that is to say that on sputtering of the glass, some constituents are more easily deposited onto the gap-defining surfaces than other constituents, so that the composition of the glass after sputtering is not equal to the composition of the starting glass.
  • the invention provides a glass which does not have the above-mentioned disadvantage.
  • the magnetic head is characterized in that the layer of non-magnetizable material consists of a mixture of 95-100% of a glass containing 12-20% by weight of Al 2 O 3 , 40-48% by weight of B 2 O 3 and a total of 35-45% by weight of one or more of the oxides BaO, CaO or SrO, and 0-5% by weight of additional constituents.
  • the method according to the invention is further preferably characterized in that a layer of non-magnetizable material consisting of a glass containing 12-20% by weight of Al 2 O 3 , 40-48% by weight of B 2 O 3 and a total of 35-45% by weight of one or more of the oxides BaO, CaO or SrO is used.
  • a glass having a composition as specified above can be deposited by sputtering on a gap-defining surface with a composition which corresponds to the composition of the glass used as the starting material.
  • the magnetic head in accordance with the invention is characterized in that the glass has the following composition: 16% by weight of Al 2 O 3 , 44% by weight of B 2 O 3 and a total of 40% by weight of one or more of the oxides BaO, CaO or SrO. Good results were obtained with a glass containing 40% by weight of BaO.
  • a second layer consisting of a non-magnetizable metal, metal oxide, metal boride, metal nitride, silicon oxide or a ferrite which is non-magnetizable at ambient temperature, is provided between the layer of non-magnetizable material and the core of magnetizable material.
  • the method in accordance with the invention preferably employs a glass which contains 16% by weight of Al 2 O 3 , 44% by weight of B 2 O 3 and a total of 40% by weight of one or more of the oxides BaO, CaO or SrO, or, which is still more preferred, 40% by weight of BaO.
  • a first layer consisting of a non-magnetizable metal, metal oxide, metal boride, metal nitride, silicon oxide or a ferrite which is non-magnetizable at ambient temperature, is first deposited on the two gap-defining surfaces, whereafter the layer of non-magnetizable material is provided on at least one of the gap-defining surfaces.
  • an (intermediate) layer between the glass and the magnetic material pole pieces has the advantage that dissolving of the magnetic material in the glass of the gap can almost completely be prevented. Consequently, the layer of non-magnetizable material in the gap cannot be contaminated by more than 5% by weight of constituents from the magnetic material or from the intermediate layer.
  • FIG. 1 shows a block of ferrite which is used as the starting material
  • FIG. 2 shows a machined pole piece
  • FIG. 3A and FIG. 3B show the applied layers for the formation of the useful gap
  • FIG. 4A and FIG. 4B shows the layers provided for the formation of the back gap
  • FIG. 5 shows the pole pieces assembled to form a head
  • FIG. 6 shows a magnetic head comprising an operative face
  • FIG. 7 shows the final magnetic head.
  • a block of material 10 which may be manufactured from polycrystalline (sintered) or monocrystalline ferrite (FIG. 1) is given the shape shown in FIG. 2 by means of standard techniques. As shown in FIG. 2, two slots 14 and 16 are found in the block and the faces 18, 20 and 22 are polished so as to serve as gap-defining surfaces.
  • First layers 24 and 26 are provided on the faces 18 and 22, respectively (see FIG. 3A) by using known techniques of masking and deposition. By masking the central face 20 no deposition is found thereon. These first layers 24 and 26 should comprise a non-magnetizable material which does not, or only to a very low extent, reacts with the ferrite.
  • Suitable materials for this purpose are certain nitrides and borides (for example boron nitride and silicon nitride), metals (for example Cr), metal oxides (for example oxides of Be, Mg, Al, Ti, Zr, Sn or Ta), silicon oxide and ferrite which is non-magnetizable at ambient temperature; most of these materials can easily be deposited by means of a sputtering method.
  • nitrides and borides for example boron nitride and silicon nitride
  • metals for example Cr
  • metal oxides for example oxides of Be, Mg, Al, Ti, Zr, Sn or Ta
  • silicon oxide and ferrite which is non-magnetizable at ambient temperature
  • tin oxide can be deposited by means of a spraying method, for example starting from SnCl 4 , at a temperature of ⁇ 500° C.
  • a good manner of depositing a thin layer of SiO 2 is also that of the so-called reactive vapour deposition.
  • a mixture of SiH 4 and O 2 is fed into a furnace which is kept at a temperature of approximately ⁇ 400° C. and in which the pole pieces are present.
  • a homogeneous layer of SiO 2 appears to form on the pole pieces.
  • Second layers 28 and 30 are deposited on the first layers 24 and 26, respectively.
  • These second layers consist of a glass comprising 12-20% by weight of Al 2 O 3 , 40-48% by weight of B 2 O 3 and a total of 35-45% by weight of one or more of the oxides BaO, CaO or SrO.
  • a suitable glass has, for example, 16% by weight of Al 2 O 3 , 44% by weight of B 2 O 3 and 40% by weight of BaO. This glass allows quantitative deposition by means of sputtering.
  • First and second layers are provided on a second pole piece (FIG. 3B) in the same manner as described above. These layers are provided with the same indices as the corresponding layers in FIG. 3A.
  • the layers deposited on the pole pieces are covered with a mask and layers for forming the back gap are deposited on the non-covered faces 20.
  • a material is preferably used having a comparatively large permeability ( ⁇ >1) so that a back gap is formed having a reluctance which is considerably smaller than that of the operative gap.
  • the pole pieces are then bonded to one another with the glass layers in contact (FIG. 5) and heated in an oven at a temperature which is sufficiently high to soften the glass layer (for example approximately 650°), the pole pieces being pressed against each other at a pressure of 20-70 kg/cm 2 .
  • the pole pieces are rigidly bonded together and can then be further machined to obtain a magnetic head of the desired shape.
  • the assembly can, for example, be machined and polished in such manner that the assembly shown in FIG. 6 is obtained, which has an operative face. As is shown in FIG. 7, said assembly can be sliced into separate segments which each constitute a magnetic head.
  • the layers 28 and 30 may become mixed, by diffusion with 0-5% by weight of constituents originating from the layers 24 or from the material 10.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Glass Compositions (AREA)
  • Magnetic Heads (AREA)

Abstract

Magnetic head and method of producing a magnetic head which is formed by a core assembled from two pole pieces. At least one layer of a non-magnetizable material which forms the useful gap is provided between the pole pieces. One embodiment of the method includes the step of deposition on the pole pieces by means of a sputtering method a layer of a glass which comprises 12-20% by weight of Al2 O3, 40-48% by weight of B2 O3 and a total of 35-45% by weight of one or more of the oxides BaO, CaO or SrO. Thereafter the pole pieces are pressed together, with the glass layers in contact, and bonded together by heating the glass to the softening point, followed by cooling.

Description

The invention relates to a magnetic head having a core of a magnetizable material which is interrupted by a gap in which at least one layer of a non-magnetizable material has been provided, and to a method of producing a magnetic head, the method comprising the following steps: The formation of a first and a second pole piece of a magnetic material; the machining of a face of each of the pole pieces in such manner as to serve as a gap-defining surface; the provision of at least one layer of a non-magnetizable material on the gap-defining surface of at least one of the two pole pieces; the joining of the gap-defining surfaces of the two pole pieces provided with the said gap layer to secure them together, whereafter a winding is provided around at least one of the pole pieces.
Magnetic heads are used to record, reproduce and/or erase magnetic information. They are used in, for example, tape recorders for recording and/or reproducing sound information or picture information.
United Kingdom Patent Specification No. 1,317,634 discloses such a magnetic head and a method of producing same. With the known magnetic head the layer of non-magnetizable material consists of a glass having a softening point of 450°-650° C., for example a glass containing 60% by weight of PbO, 16% by weight of SiO2, 14% by weight of B2 O3 and 10% by weight of ZnO. The glass may be provided by means of sputtering. According to this prior art a second layer, consisting of a non-magnetisable material, metal oxide, metal boride, metal nitride, silicon oxide or a ferrite which is non-magnetizable at ambient temperature, may be provided between the layer of non-magnetizable material and the core of magnetisable material.
The glass used in the known magnetic head has the disadvantage that the composition of the glass is not constant, that is to say that on sputtering of the glass, some constituents are more easily deposited onto the gap-defining surfaces than other constituents, so that the composition of the glass after sputtering is not equal to the composition of the starting glass.
The invention provides a glass which does not have the above-mentioned disadvantage.
According to the invention, the magnetic head is characterized in that the layer of non-magnetizable material consists of a mixture of 95-100% of a glass containing 12-20% by weight of Al2 O3, 40-48% by weight of B2 O3 and a total of 35-45% by weight of one or more of the oxides BaO, CaO or SrO, and 0-5% by weight of additional constituents.
The method according to the invention is further preferably characterized in that a layer of non-magnetizable material consisting of a glass containing 12-20% by weight of Al2 O3, 40-48% by weight of B2 O3 and a total of 35-45% by weight of one or more of the oxides BaO, CaO or SrO is used.
Quite surprisingly it was found that a glass having a composition as specified above can be deposited by sputtering on a gap-defining surface with a composition which corresponds to the composition of the glass used as the starting material.
Preferably, the magnetic head in accordance with the invention is characterized in that the glass has the following composition: 16% by weight of Al2 O3, 44% by weight of B2 O3 and a total of 40% by weight of one or more of the oxides BaO, CaO or SrO. Good results were obtained with a glass containing 40% by weight of BaO. Preferably, a second layer consisting of a non-magnetizable metal, metal oxide, metal boride, metal nitride, silicon oxide or a ferrite which is non-magnetizable at ambient temperature, is provided between the layer of non-magnetizable material and the core of magnetizable material.
The method in accordance with the invention preferably employs a glass which contains 16% by weight of Al2 O3, 44% by weight of B2 O3 and a total of 40% by weight of one or more of the oxides BaO, CaO or SrO, or, which is still more preferred, 40% by weight of BaO. Good results were obtained when a first layer, consisting of a non-magnetizable metal, metal oxide, metal boride, metal nitride, silicon oxide or a ferrite which is non-magnetizable at ambient temperature, is first deposited on the two gap-defining surfaces, whereafter the layer of non-magnetizable material is provided on at least one of the gap-defining surfaces.
The use of an (intermediate) layer between the glass and the magnetic material pole pieces has the advantage that dissolving of the magnetic material in the glass of the gap can almost completely be prevented. Consequently, the layer of non-magnetizable material in the gap cannot be contaminated by more than 5% by weight of constituents from the magnetic material or from the intermediate layer.
The invention will now be further explained by way of non-limiting example with reference to the drawing in which:
FIG. 1 shows a block of ferrite which is used as the starting material,
FIG. 2 shows a machined pole piece,
FIG. 3A and FIG. 3B show the applied layers for the formation of the useful gap,
FIG. 4A and FIG. 4B shows the layers provided for the formation of the back gap,
FIG. 5 shows the pole pieces assembled to form a head,
FIG. 6 shows a magnetic head comprising an operative face,
FIG. 7 shows the final magnetic head.
A block of material 10 which may be manufactured from polycrystalline (sintered) or monocrystalline ferrite (FIG. 1) is given the shape shown in FIG. 2 by means of standard techniques. As shown in FIG. 2, two slots 14 and 16 are found in the block and the faces 18, 20 and 22 are polished so as to serve as gap-defining surfaces.
First layers 24 and 26 are provided on the faces 18 and 22, respectively (see FIG. 3A) by using known techniques of masking and deposition. By masking the central face 20 no deposition is found thereon. These first layers 24 and 26 should comprise a non-magnetizable material which does not, or only to a very low extent, reacts with the ferrite. Suitable materials for this purpose are certain nitrides and borides (for example boron nitride and silicon nitride), metals (for example Cr), metal oxides (for example oxides of Be, Mg, Al, Ti, Zr, Sn or Ta), silicon oxide and ferrite which is non-magnetizable at ambient temperature; most of these materials can easily be deposited by means of a sputtering method.
It should be noted that tin oxide can be deposited by means of a spraying method, for example starting from SnCl4, at a temperature of ±500° C.
A good manner of depositing a thin layer of SiO2 is also that of the so-called reactive vapour deposition. In this method a mixture of SiH4 and O2 is fed into a furnace which is kept at a temperature of approximately ±400° C. and in which the pole pieces are present. A homogeneous layer of SiO2 appears to form on the pole pieces.
Second layers 28 and 30 are deposited on the first layers 24 and 26, respectively. These second layers consist of a glass comprising 12-20% by weight of Al2 O3, 40-48% by weight of B2 O3 and a total of 35-45% by weight of one or more of the oxides BaO, CaO or SrO. A suitable glass has, for example, 16% by weight of Al2 O3, 44% by weight of B2 O3 and 40% by weight of BaO. This glass allows quantitative deposition by means of sputtering.
The sum of the thicknesses of the layers 24 and 28 determine the ultimate gap length. First and second layers are provided on a second pole piece (FIG. 3B) in the same manner as described above. These layers are provided with the same indices as the corresponding layers in FIG. 3A.
In the following stage of the method (FIGS. 4A and 4B) the layers deposited on the pole pieces are covered with a mask and layers for forming the back gap are deposited on the non-covered faces 20. For this purpose a material is preferably used having a comparatively large permeability (μ>1) so that a back gap is formed having a reluctance which is considerably smaller than that of the operative gap.
The pole pieces are then bonded to one another with the glass layers in contact (FIG. 5) and heated in an oven at a temperature which is sufficiently high to soften the glass layer (for example approximately 650°), the pole pieces being pressed against each other at a pressure of 20-70 kg/cm2. After cooling, the pole pieces are rigidly bonded together and can then be further machined to obtain a magnetic head of the desired shape. The assembly can, for example, be machined and polished in such manner that the assembly shown in FIG. 6 is obtained, which has an operative face. As is shown in FIG. 7, said assembly can be sliced into separate segments which each constitute a magnetic head.
After bonding of the pole pieces the layers 28 and 30 may become mixed, by diffusion with 0-5% by weight of constituents originating from the layers 24 or from the material 10.

Claims (5)

What is claimed is:
1. A magnetic head having a core of a magnetizable material which is interrupted by a gap in which at least one layer of a substantially non-magnetizable material has been provided, characterized in that one layer of substantially non-magnetizable material consists of a mixture of 95-100% of a glass comprising 12-20% by weight of Al2 O3, 40-48% by weight of B2 O3 and a total of 35-45% by weight of one or more of the oxides BaO, CaO or SrO and 0-5% by weight of additional constituents.
2. A magnetic head as claimed in claim 1, characterized in that the glass consists of 16% by weight of Al2 O3, 44% by weight of B2 O3 and a total of 40% by weight of one or more of the oxides BaO, CaO or SrO.
3. A magnetic head as claimed in claim 2, characterized in that the glass comprises 40% by weight of BaO.
4. A magnetic head as claimed in claim 1, 2 or 3, characterized in that a second layer consisting of a non-magnetizable metal, metal oxide, metal boride, metal nitride, silicon oxide or a ferrite which is non-magnetizable at ambient temperature, is provided between the layer of substantially non-magnetizable material containing glass and said core.
5. A magnetic head as claimed in claim 4, characterized in that the additional constituents of the magnetizable material or of the second layer as claimed in claim 4 are diffused into said glass containing layer of substantially non-magnetizable material.
US06/200,112 1980-06-18 1980-10-24 Magnetic head, method of producing the magnetic head Expired - Lifetime US4392167A (en)

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Application Number Priority Date Filing Date Title
NL8003518 1980-06-18
NL8003518A NL8003518A (en) 1980-06-18 1980-06-18 MAGNETIC HEAD, METHOD FOR MANUFACTURING A MAGNETIC HEAD.

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JP (1) JPS5727417A (en)
AT (1) AT371264B (en)
DE (1) DE3123574A1 (en)
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Cited By (11)

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Publication number Priority date Publication date Assignee Title
US4544974A (en) * 1983-10-20 1985-10-01 Eastman Kodak Company Alumina glass composition and magnetic head incorporating same
US4600957A (en) * 1982-05-19 1986-07-15 U. S. Philips Corporation Glass-bonded magnetic head having diffusion barriers
US4667259A (en) * 1984-04-19 1987-05-19 Hitachi Metals, Ltd. Non-magnetic part in magnetic head assembly
US4796114A (en) * 1984-10-02 1989-01-03 Fuji Photo Film Co., Ltd. Rotary head assembly with rigid adhesive bonding pole tips
US4819113A (en) * 1984-03-29 1989-04-04 Sony Corporation Magnetic transducer head with inclined magnetic gap
US4828966A (en) * 1987-12-04 1989-05-09 Digital Equipment Corporation Method for producing hall effect sensor for magnetic recording head
US4901179A (en) * 1985-02-15 1990-02-13 Matsushita Electric Industrial Co., Ltd. Magnetic head having a laminated structure
US4941064A (en) * 1985-03-20 1990-07-10 Hitachi Maxell, Ltd. Magnetic head having a pair of cores in which the opposing surfaces thereof are coated with a non-magnetic layer and a low melting point glass layer
US5055957A (en) * 1989-06-19 1991-10-08 International Business Machines Corporation Method of making low wear glass for magnetic heads
US5211734A (en) * 1989-03-31 1993-05-18 Tdk Corporation Method for making a magnetic head having surface-reinforced glass
US5481422A (en) * 1992-07-24 1996-01-02 Matsushita Electric Industrial Co., Ltd. Magnetic head with metallic magnetic film and protective film means

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JPH0654527B2 (en) * 1984-11-26 1994-07-20 ソニー株式会社 Magnetic head
JPH0528413U (en) * 1991-09-26 1993-04-16 帝国ピストンリング株式会社 Electronic dehumidifier

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US3249700A (en) * 1960-09-27 1966-05-03 Philips Corp Magnetic heads with means for preventing side erosion
US3375575A (en) * 1962-05-04 1968-04-02 Philips Corp Heat and pressure glass bonding of spaced magnetic head portions by forming and using glass over flow channels
US3458926A (en) * 1965-10-08 1969-08-05 Ibm Method of forming a glass filled gap
US3721000A (en) * 1968-03-15 1973-03-20 Sony Corp Method of making a magnetic head
US3544982A (en) * 1968-05-01 1970-12-01 Rca Corp Multi-head magnetic transducer
US3624897A (en) * 1969-07-25 1971-12-07 Bell & Howell Co Method of making a ferrite head
US3781486A (en) * 1972-04-26 1973-12-25 Avco Corp Magnetic head transducer
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Cited By (14)

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Publication number Priority date Publication date Assignee Title
US4600957A (en) * 1982-05-19 1986-07-15 U. S. Philips Corporation Glass-bonded magnetic head having diffusion barriers
US4665612A (en) * 1982-05-19 1987-05-19 U.S. Philips Corporation Method of manufacturing a glass-bonded magnetic head having diffusion barriers
US4544974A (en) * 1983-10-20 1985-10-01 Eastman Kodak Company Alumina glass composition and magnetic head incorporating same
US4819113A (en) * 1984-03-29 1989-04-04 Sony Corporation Magnetic transducer head with inclined magnetic gap
US4667259A (en) * 1984-04-19 1987-05-19 Hitachi Metals, Ltd. Non-magnetic part in magnetic head assembly
US4796114A (en) * 1984-10-02 1989-01-03 Fuji Photo Film Co., Ltd. Rotary head assembly with rigid adhesive bonding pole tips
US4901179A (en) * 1985-02-15 1990-02-13 Matsushita Electric Industrial Co., Ltd. Magnetic head having a laminated structure
US4941064A (en) * 1985-03-20 1990-07-10 Hitachi Maxell, Ltd. Magnetic head having a pair of cores in which the opposing surfaces thereof are coated with a non-magnetic layer and a low melting point glass layer
WO1989006054A2 (en) * 1987-12-04 1989-06-29 Digital Equipment Corporation Method for producing hall effect sensor for magnetic recording head
US4828966A (en) * 1987-12-04 1989-05-09 Digital Equipment Corporation Method for producing hall effect sensor for magnetic recording head
WO1989006054A3 (en) * 1987-12-04 1991-09-05 Digital Equipment Corp Method for producing hall effect sensor for magnetic recording head
US5211734A (en) * 1989-03-31 1993-05-18 Tdk Corporation Method for making a magnetic head having surface-reinforced glass
US5055957A (en) * 1989-06-19 1991-10-08 International Business Machines Corporation Method of making low wear glass for magnetic heads
US5481422A (en) * 1992-07-24 1996-01-02 Matsushita Electric Industrial Co., Ltd. Magnetic head with metallic magnetic film and protective film means

Also Published As

Publication number Publication date
GB2079515B (en) 1984-09-12
NL8003518A (en) 1982-01-18
ATA266381A (en) 1982-10-15
AT371264B (en) 1983-06-10
FR2485238B1 (en) 1984-12-14
DE3123574A1 (en) 1982-06-03
JPS5727417A (en) 1982-02-13
FR2485238A1 (en) 1981-12-24
HK98484A (en) 1984-12-28
GB2079515A (en) 1982-01-20
JPH0258684B2 (en) 1990-12-10

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